During meiosis, one round of genome replication is followed by two nuclear divisions to produce haploid gametes. The events of meiosis are sufficiently specialized that the mechanisms coupling them together are likely to differ from those in vegetative cells. To further understand the mechanism linking replication and recombination in fission yeast meiosis, I am examining the conserved meiotic-specific endonuclease, Rec12p (S. cerevisiae Spo11p). Rec12p is responsible for catalyzing the formation of double-strand breaks, which is a hallmark of recombination. Fission yeast cells lacking rec12+ are deficient for recombination, which is required for normal chromosome pairing and segregation during the meiotic divisions. Aberrant divisions and improper chromosome segregation in humans account for approximately 10-25% of all aneuploidies, which usually result in miscarriages. I have epitope tagged Rec12p and am investigating whether its localization and activation are linked to replication fork passage. [unreadable] [unreadable]